Tug/barge latching mechanism

ABSTRACT

A self-latching self-releasing mechanism for coupling and releasably locking a marine tug to a barge includes, in a preferred form, a non-powered latching mechanism of the keeper type mounted at the aft end of the barge and a power-driven latch coupling mechanism mounted on the fore end of the tug. The powerdriven latch coupling mechanism includes a latch bar mounted at the forward end of an elongated tubular nut adapted to be driven forwardly and rearwardly in the axial direction of the tubular nut by a power-driven screw shaft. Provision is made for rotating the tubular nut, and hence the latch bar, through 90*, to effect latching and unlatching. The rearward end of the screw shaft is supported for rotation in the housing of the power drive which in turn is supported for universal movement on a stub mounted in a self-aligning spherical bearing in a support housing mounted on the tug. Axial or translational thrust forces are transmitted through the screw shaft and its power drive housing to the support housing. The power drive and its housing move axially with any axial movement of the screw, and hence are not subjected to the axial thrust forces. Self-latching and self-releasing of the latching mechanism is accomplished and controlled by the direction of rotation of the tubular nut on the screw shaft.

United States Patent 91 Stratienko et a1.

[451 Aug. 6, 1974 TUG/BARGE LATCHING MECHANISM [75] Inventors: Andrew Stratienko, Wyndmoor;

Robert J. Kornsey, Hatfield, both of Pa.

[73] Assignee: Philadelphia Gear Corporation,

King of Prussia, Pa.

22 Filed: Sept. 4, 1973 211 Appl.No.:393,913

[52] US. Cl. 114/235 A, 280/482 [51] Int. Cl B63b 21/00 [58] Field of Search 114/235 R, 235 A, 77 R,

114/77 A; 213/85, 96, 97, 182, 184; 280/504, 482, 511, 479; 24/221 R, 221 A; 403/348, 349

[56] I References Cited UNITED STATES PATENTS 2,743,118 3/1956 Dotson 280/511 Primary ExaminerTrygve M. Blix Assistant Examiner-Sherman D. Basinger Attorney, Agent, or Firm-Paul & Paul 5 7] ABSTRACT A self-latching self-releasing mechanism for Coupling and releasably locking a marine tug to a barge includes, in a preferred form, a non-powered latching mechanism of the keeper type mounted at the aft end of the barge and a power-driven latch coupling mechanism mounted on the fore end of the tug. The powerdriven latch coupling mechanism includes a latch bar mounted at the forward end of an elongated tubular nut adapted to be driven forwardly and rearwardly in the axial direction of the tubular nut by a powerdriven screw shaft. Provision is made for rotating the tubular nut, and hence the latch bar, through 90, to effect latching and unlatching. The rearward end of the screw shaft is supported for rotation in the housing of the power drive which in turn is supported for universal movement on a stub mounted in a self-aligning spherical bearing in a support housing mounted on the tug. Axial or translational thrust forces are transmitted through the screw shaft and its power drive housing to the support housing. The power drive and its housing move axially with any axial movement of the screw, and hence are not subjected to the axial thrust forces. Self-latching and self-releasing of the latching mechanism is accomplished and controlled by the direction of rotation of the tubular nut on the screw shaft.

12 Claims, 9 Drawing Figures PATENIE AUG 6l374 SHEET 1 OF 5 PAIENIEDMIE 81m SHEET 2 0F 5 mamm l e m sum 3 or s PATENTED W5 SW SHEET & [If 5 PAIENIEB M18 6 i974 SHEU 5 Bf 5 1 TUG/BARGE LATCIIING MECHANISM BACKGROUND OF THE INVENTION This invention relates to mechanisms for coupling a marine tug to a barge.

More particularly, the invention relates to mechanisms for coupling together and locking releasably a tug and a barge in tandem arrangement, as distinguished from the alongside arrangement which is frequently used in harbor work.

The invention relates particularly to tug/barge coupling means where the aft end of the barge is provided with a recess or notch for receiving the prow or fore part of a tug which is to be releasably latched to the barge for pulling or pushing the barge which in most instances will be much larger than the tug.

SUMMARY OF THE INVENTION A principal object of the invention is to provide a self-latching, self-releasing coupling mechanism for connecting a tug and barge together, with all of the power-driven components being located on the tug.

A further object is to provide a latching mechanism of the foregoing type in which the tug and barge, when latched together, are effectively integrated, with no freedom of relative motion between the tug and the barge;

A further object is to provide a power-driven, selflatching, self-releasing coupling mechanism for a tug and a barge for effecting a rigid connection therebetween, but with provision for aligning the component parts of the mechanism located on the tug with that located on the barge.

The foregoing, as well as other objects of the invention, are accomplished, in accordance with a preferred form of the invention, by providing a non-powered latch keeper mechanism on the barge and by providing on the tug a power-driven latch coupling mechanism which includes a latch bar mounted at the forward end of a tubular nut adapted to be moved in the forward and rearward axial directions of the nut by rotation of a screw driven by a power drive assembly. self latching and self-releasing of the latching mechanism is controlled by the direction of rotation of the tubular nut on the power-driven screw shaft.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic elevational illustration of a marine tug/barge coupling and latching mechanism, according to one embodiment of the present invention, the barge and tug being shown in unlatched positions, with the barge on the left and the tug on the right.

FIG. 2 is a schematic elevational illustration similar to that of FIG. 1 but showing the barge and tug in latched positions.

FIG. 3 is an end view in section, looking along the line 3--3 of FIG. 2.

FIG. 4 is an elevational view, in section, of the coupling mechanism on the tug, as seen looking along the bent line 4-4 of FIG. 3.

FIG. 5 is an end view of a support frame for the tubular nut, mounted on the tug, as seen looking down along the line 55 of FIG. 2.

FIG. 6 is a view looking along the line 6-6 of FIG. 5.

FIG. 7 is a perspective exploded illustration of the tubular-nut support frame mechanism on the tug.

FIG. 8 is a plan view, in section, of the latch keeper housing on the barge.

FIG. 9 is an end view, in section, of the latch keeper housing on the barge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Illustrated schematically, at the left-hand side of FIG. 1, is the aft end of a barge B having mounted thereon a non-powered keeper-type latch mechanism. Illustrated schematically at the right-hand portion of FIG. 1, is the fore end of a tug T having mounted thereon a power-drive form of latch coupling mechanism adapted to co-operate with the keeper mechanism on the barge B to automatically couple and uncouple the tug and barge vessels. The coupling mechanism on the Tug T will be described first.

Referring to FIGS. 2, 3 and 4, as well as FIG. 1, a latch bar 45, having a width greater than its height and preferably of generally rectangular cross section, and having convex faces, is screwed or otherwise fitted into the forward end of a tube 42 and keyed thereto as by key 43.

Tube 42, together with a collar 41 and a captive nut 40, form a tubular nut N. So far as operation is concerned, tubular nut N could be a single integral piece, but, for assembly reasons, tube 42 is internally threaded at its rearward end and screwed into a collar 41, with a nut 40 being captive within collar 41 and tube 42. Tube 42 is provided with a pair of exterior keys 46 which are at 180 spacing and which extend longitudinally along the exterior surface of the tube. These keys 46 are seen in section in FIG. 5.

The tubular nut N (40, 41, 42) is threaded on a elongated externally threaded shaft or screw 20. The forward end of screw shaft 20 is of reduced diameter and non-threaded, and keyed thereto, as by key 49, is a sleeve bushing 44, which supports the forward end of screw 20 within the tube 42 of the tubular nut N.

Screw 20 extends rearwardly from tube 42 through the forward portion of a power drive housing 30 and into a rearward portion which is secured, as by bolts, to the forward portion. The rearward portion 130 is secured, as by welding, to a stub shaft 131 which is screwed into a square nut 12 having spherical forward and rearward faces for universal movement in a ball type socket 13 mounted in a support housing 10 on the tug T. A key 132 locks the stub shaft 131 against rotation in the square nut 12, thereby preventing rotational movement of power-drive housing 30 in response to torque forces imposed in the housing 30.

Supported in housing 30 is a power drive which comprises a plurality of electric drive motors 32 (four being shown in FIG. 3) which are connected through suitable couplings 33 to pinions 34 which are engaged at spaced-apart positions with the peripheral teeth of a bull gear 35 mounted on and keyed to screw shaft 20, as by key 36. If desired, a positive brake (not shown) may be applied to one or more of the pinion shafts to lock the screw shaft 20 against rotation when it is not being driven by the power drive.

Screw shaft 20 is adapted for rotation in housing 30 on a roller bearing assembly 39 located forwardly of the bull gear 35, and by a pair of thrust bearing assemblies 37 and 38 located rearwardly of bull gear 35 and retained by a retaining nut 23 screwed on the end of screw shaft 20.

Reference is now made to FIG. 7 which is an exploded perspective view of a support-and-guide mechanismin a housing 50 which, as seen in FIGS. 1, 2, and 4-6, is mounted on the fore deck of tug T and through which the tube 42 passes for supporting the forward end of the tube while allowing for limited movement of the tube in all radial directions relative to the longitudinal axis of the tube.

Support-and-guide housing 50 includes a rearward frame member 51 and a forward frame member 52. Each of these frame members 51 and 52 is provided with two pairs of support legs 53 and 54, respectively, and secured, as by pins 55 and 56, to pedestal blocks 57 and 58 secured, as by welding, to the deck of tug T. Each of the frame members 51 and 52 is provided with a large aperture, identified as 59 and 60 respectfully, through which tube 42 passes. These apertures are illustrated as vertically rectangular, but need not be. For example, they could be vertically oval. The rearward frame member 51 includes a pair of vertical side rails 61 which function as guide rails for a slide frame 64. A pair of support pins 62 extend forwardly from the rearward frame member 51 and pass through holes 63 in the forward frame member 52 for supporting the forward frame 52 thereon. Any suitable means may be used for securing the forward frame on the pins 62.

Within the housing 50 of the support-and-guide mechanism, between the rearward frame member 51 and the forward frame member 52, is a slide frame 64 which is slidable up and down on side rails 61 within the housing 50. The slide frame 64 comprises a rectangular box member 65 and a face plate 66, which is supported on the box member 65 as by four pins 67. These four pins 67 also support four pairs of rollers 68, which support and guide a pair of annular disc 79 for rotary movement within the slide frame 64.

The rearward wall of box member 65 of slide frame 64 has therein a generally circular aperture 70 whose peripheral edges are defined by two pairs of opposing arcuate surfaces 71 and 72 which lie on circles of different diameters. The one pair of opposing arcuate surfaces 71 lie on a small-diameter circle which corresponds to the outside diameter of tube 42 exclusive of its keys 46. The other pair of opposing arcuate surfaces 72 lie on a larger-diameter circle which corresponds to the overall diameter of tube 42 including the keys 46. At the junction of the arcuate surfaces 71 and 72 are radial surfaces 26 and 27 which function as stops'for keys 46, as will become clear.

An aperture 73, identically shaped and sized as aperture 70, is provided in the face plate 66 of the slide frame 64 and the corresponding pairs of arcuate surfaces in face plate 66, and the corresponding key stop surfaces, are given similar reference numerals, followed by the suffix a, as indicated in FIG. 7.

Provided in one form of the invention, but not essential to the shaft-mounted screw-shaft drive form of latching mechanism, is a pair of fluid cylinders 74,

faces 72. The piston heads 77 are pinned to ears 78 of a pair of annular discs 79, seen in FIG. 7. Discs 79 have circular apertures having a diameter equal to the diameter of the smaller-diameter arcuate surfaces 71 of slide frame 64. As previously indicated, this diameter (71) corresponds to the outside diameter of tube 42 exclusive of keys 46. The circular edge of the'opening in discs 79 is provided with a pair of opposing recesses r notches 25, at 180 spacing, through which pass keys 46 of tube 42. The outer circular edges of disc 79 are supported and guided for rotational movement by four sets of rollers 68 mounted on pins 67 in slide frame 64, as indicated in FIG. and as seen in section in FIG. 6.

Referring now to FIGS. 1, 2, 8 and 9, mounted on the barge B, at the aft end thereof, is a non-powered latch keeper housing 80 having a rearwardly-extending open-ended section 81 which projects beyond the rear end of the barge B. Section 81 has an inclined ramp 82 which extends rearwardly downwardly, and the side walls 83 of section 81 are divergent rearwardly, as seen in FIGS. 8 and 9.

Between latch keeper housing 80 and its rearwardly extending section 81 is a wall 84 having a central aperture 85 therein and a pair of abutment blocks 95 above and below the aperture. The shape and size of aperture 85 corresponds to the shape and size of latch bar 45 when in one of its two positions. In the illustrated emwhich may be hydraulic or pneumatic, and which are supported for pivotal movement in pivot brackets 76 in the upper edge surface of 65, seen in FIG. 7. The pistons of the cylinders 74 are extendible and retractable in generally vertical directions, but the pivotal mountings 76 allow for the piston heads 77 to move along arcuate paths corresponding to the arcuate surbodiment, aperture 85 is wider than it is high, and is of such shape and size as to allow latch bar 45 to pass therethrough only when the latch bar 45 is in the horizontal or unlatching position, as illustrated in FIG. 1 and as shown in phantom in FIGS. 8 and 9.

The forward wall 86 of housing is provided with an abutment plate 87 having a concave recess 88 for receiving the convex face of latch bar 45. The upper portion of one side of housing 80, the left side as viewed in FIG. 9, and the lower portion of the other side of housing 80, the right side as viewed in FIG. 9, are provided with abutment stop members 91 and 92 which extend the full length of housing 80 and which stop counterclockwise rotation, as viewed in FIG. 9, of latch bar 45 beyond its vertical or latching position.

Provided at the rearward portion only of housing 80, at the upper right and lower left portions as viewed in FIG. 9, are abutment stop members 93 and 94 which extend for only a portion of the full length of housing 80. These short stop members 93 and 94, in combination with the abutment stop members 91 and 92, prevent rotation of the vertical latch bar 45 in either direction, when the latch bar 45 is at the rearward end of the housing 80. In this position, the latch bar 45 is latched and locked. Counterclockwise rotation of latch bar 45 is allowed, as viewed in FIG. 9, only after the latch bar 45 has been moved fowardly toward the recessed abutment plate 86 beyond the forward ends of the shortlength stop members 93 and 94.

OPERATION To latch the tug T to the barge B, tug T is maneuvered into a position immediately rearward of barge B. In some instances, barge B will be especially designed and built for a tug connection and will have a notch or slot in its rearward end portion for receiving the bow or forward portion of tug T.

When tug T has been maneuvered into a position in alignment with barge B, which is the position indicated in FIG. 1, drive motors 32 of the shaft-mounted drive are energized to drive pinions 34 and bull gear 35 rotationally, thereby driving rotationally the screw shaft 20 in a direction to move the tubular nut N forwardly on the screw toward the barge B.

In the operation of the latching mechanism now being described, it will be assumed that the piston cylinders 74 have not been provided. These cylinders are optional; they are not essential, as will become clear.

As illustrated, to move the tubular nut N forwardly, i.e., toward the barge B, the screw 20 is rotated counterclockwise, as viewed looking from the tug T toward the barge B. As viewed in FIGS. 5, 7 and 9, this rotation of screw 20 is clockwise. When screw 20 is first so driven, due to the frictional resistance between the threads of the nut 40 and the screw 20, the tubular nut N will roate with the screw 20 through 90 until the keys 46 abut against the stops 26, 26a, in slide 64. R- tation of the tubular nut N then stops. The arrangement is such that when the keys 46 of tube 42 meet the stop surfaces 26, 26a, the latch bar 45 will have been turned to the horizontal position, illustrated in FIG. 1 and seen in phantom in FIG. 8. Thereafter, as rotation of screw 20 continues, the nut N moves forwardly toward the barge B, with the latch bar 45 remaining in the horizontal position.

If, when latch bar 45 reaches the barge B, the latch bar is lower than the deck surfaces of the barge B, the ramp surface 82 will cam the latch bar 45upwardly, and the resulting upward movement of tube 42 will cause slide frame 64 to slide upwardly in housing 50.

If, when the latch bar 45 reaches the barge B, the latch bar is to the left or to the right of center, the latch bar 45 will be cammed toward center by the forwardly convergent side walls 83, as indicated in plan view in phantom in FIG. 8. The resulting lateral movement of tube 42 will cause housing 50 to move laterally on its legs 53, 54,.as is indicated in phantom in FIG. 5.

In the movements of latch bar 45 and tube 42, vertically and laterally, referred to above, the rear end of the screw shaft 20, the power-drive housing 30, and the stub shaft 131, move universally, being supported in the universal joint 12, 13 in housing 10.

As forward movement of latch bar 45 in the horizontal position continues, the latch bar 45 passes through aperture 85 in the rearward wall 84 of housing 80 and enters into the latch keeper housing. The forward drive is continued until the convex forward face of the latch bar 45 abuts against the concave recess 88 of abutment plate 87. The direction of the reversible motors 32 is then reversed and the screw shaft 20 is now driven in the opposite or clockwise direction, as viewed looking from the tug T toward the barge B (counter-clockwise as viewed in FIGS. 5, 7 and 9). When the direction of rotation of screw 20 is reversed, as just indicated, the frictional resistance between the convex face of the latch bar 45 and the concave surface of recess 88 may prevent the latch bar 45 from rotating, thereby causing rearward movement of the nut N on screw 20, but as soon as the latch bar 45 leaves the surface of recess 88, the tubular nut N rotates with the screw 20, due to the frictional resistance between the threads of the nut 40 and the screw 20. This rotation, counterclockwise as viewed in FIG. 5, continues for 90, until the keys 46 encounter and are stopped by the stop surfaces 27, 27a. This 90 rotation of the tubular nut N rotates the latch bar 45 through 90, counterclockwise as viewed in FIG. 9, from the horizontal to the vertical position shown in solid line in FIG. 9. Continued rotation of screw shaft 20 then causes the vertically-positioned latch bar 45 to move rearwardly within the latch keeper housing until the latch bar 45 abuts against the abutment blocks 95, as illustrated in FIG. 2. The latch bar 45 is now in the fully latched position, and continued rotation of screw 20 in a direction tending to withdraw the latch bar 45 from the keeper housing 80 has the effect of drawing the tug T toward the heavier barge B until the tug T abuts tightly against the barge B, as illustrated schematically in FIG. 2.

Thereafter, the tug and barge operate as an integral unit, at least so far as thrust forces are concerned.

To unlatch the latching mechanism and decouple the tug T from the barge B, the screw shaft 20 is first driven, by its motor drive, in a direction to cause the tubular nut N and latch bar 45 to move forwardly from the latched position shown in FIG. 2. When the screw shaft 20 is first so driven (clockwise as viewed in FIG. 9) the abutment stop members 93 and 94 prevent rotation of the latch bar 45 and, accordingly, the tubular nut N will move forwardly on the screw, moving the latch bar 45 away from the blocks 95. As soon as the latch bar 45 is clear of the short-length abutment stop members 93, 94, the latch bar, due to frictional resistance between the threads of the nut 40 and the screw 20, will rotate with the screw shaft 20, and forward movement will temporarily cease. However, such rotation of the latch bar 45 will continue only through until the keys 46 of the tube 42 reach and abut against the radial stop surfaces 26, 26a of the slide 64. Since this will occur after the latch bar has rotated through 90, the position of the latch bar 45 is changed from the vertical to the horizontal position. Thereafter, with further rotational movement of the tubular nut N and the latch bar 45 prevented, the tubular nut N and the latch bar 45 will move forwardly toward the recess 88 in plate 87 of the forward wall 86 of housing 80. Continued drive of the screw shaft 20 in the forward direction, after the latch bar 45 has been seated in the recess 88 of the plate 87, will drive the tug T rearwardly away from the barge B, thereby decoupling the two vessels.

It will be seen from the foregoing description that the operation of latching and unlatching depends upon frictional resistance between the tubular nut N and the screw shaft 20 to rotate the tubular nut N and hence the latch bar 45 through 90 to effect the necessary change in the position of the latch bar.

In some cases, it may be necessary to increase the frictional resistance between the nut N and the screw shaft 20, so as to assure angular movement of the nut 40 in response to initial rotational movement of the screw shaft. This may be accomplished in a number of ways, one of which is illustrated in FIG. 4. As there illustrated, nut 40 is provided with a recess having therein a brake shoe 141 which is pressed against one or more threads (two being illustrated) of the screw shaft 20, as by a compression spring 142.

In accordance with a modification of the present invention, a positive drive is provided for assuring the necessary rotation of the tubular nut N and of the latch bar 45 through 90. This assurance is provided through a pair of fluid cylinders 74 pivotally mounted in pivot brackets 76 on the upper edge of the support-and-guide unit 64. As has already been indicated, pistons 75 of the cylinders 74 have heads 77 which are pinned to the opposite ears 78 of a pair of discs 79. It will be seen, by driving the fluid cylinders 74, as by hydraulic or pneumatic means, to extend the one piston 75 while withdrawing the other piston 75, that the pair of discs 79 will be driven rotationally on the support rollers 68 in one direction or the other, according to the drive of the pistons 75.

By the means described, either with or without the employment of the fluid cylinders and pistons 74, 75, the tug T and the barge B are automatically latched and automatically released by power drive mechanism located on the tug T. No raising and lowering of the coupling shaft is required. No manual adjustments or operations are required. The capability of ramp surface 82 to cam the latch bar 45 upwardly to the necessary latching position, accommodates to different levels of the tug deck relative to the barge deck. Movement of the latch bar 45 upwardly and downwardly is made possible by the support of the tubular nut N in the slide guide 64 of the support-and-guide housing 50. The capability of the convergent side walls 83 of the section 81 to cam the latch bar 45 toward the center axis, accommodates to misalignments in the axial or tandem directions. Lateral movement of latch bar 45 is made possible by the support of support-and-guide housing 50 on the legs 53, 54 for lateral movement in either direction. Movement of latch bar 45 in universal directions is made possible by the fact that the rear end of the screw shaft 20 is mounted in housing 30 which is supported by stub shaft 131 for universal movement in the universal joint in housing 10.

It is to be noted that none of the thrust forces (pull or push) are imposed on the power drive housing 30. Housing 30 merely rides along with any small axial movement of the screw shaft 20. All of the axial thrust forces are taken by the support housing 10. This is an important feature of the power drive disclosed in the present application.

The invention has been described as particularly suited for latching a tug to a barge. In such case, the power drive is located on the tug. However, the latching mechanism described may also be used for latching other forms of units, wherein at least one of the units is mobile.

in some installations, two or more substantially identical latching mechanisms of the type described herein may be used in parallel.

What is claimed is:

1. Apparatus for releasably coupling and latching together first and second units at least one of which is mobile, said coupling-and-latching apparatus comprismg:

A. A first powered mechanism mounted on a first mobile unit, said first mechanism including:

a. a screw shaft;

b. a reversible power drive for said screw shaft;

c. a nut engaged with said screw shaft;

d. means responsive to initial rotation of said screw shaft in either direction for allowing limited angular movement in said same direction of said nut and thereafter preventing rotational movement thereof in said same direction thereby to effect axial movement of said nut on said screw shaft in one direction or the other according to the direction of rotation of said screw shaft;

e. a latch bar on said nut and adapted to be moved angularly in response to initial rotation of said screw shaft in either direction and thereafter to be moved axially forwardly or rearwardly on said screw shaft to effect self-latching and selfunlatching of said coupling-andlatching apparatus;

B. a second non-powered mechanism on a second unit, said second mechanism including:

a. a latch-bar keeper mechanism fixed mounted on said second unit and adapted to be engaged by said latch bar for latching said bar, and for unlatching said bar, according to the angular position of said bar and to subsequent axial movement of said nut on said screw shaft.

2. Apparatus according to claim ll wherein said second mechanism includes:

a. at least one rotational stop for said latch bar preventing rotational movement of said latch bar in one direction beyond a selected angular latching position;

b. additional rotational stop for preventing rotational movement of said latch bar in either direction when said latch bar is in angular latching position and also in axial latching position.

3. Apparatus according to claim 2 wherein said latchbar keeper mechanism includes a housing having an aperture therein of a shape and size to allow passage therethrough of said latch bar when said latch bar is in angular unlatching position.

4. Apparatus according to claim 3 wherein said second mechanism includes guide means for guiding said latch bar into said housing aperture.

5. Apparatus according to claim 4 wherein:

, a. said nut has an elongated tube portion;

b. said tube is provided with rotational stop means;

c. a support housing is provided on said first mobile unit through which said elongated tube portion of said nut passes;

d. said tube support housing is constructed to allow limited movement of said tube within said support housing in all radial directions;

e. said tube support housing is constructed to cooperate with said tube stop means to allow limited angular movement of said tube portion about its center axis.

6. Apparatus according to claim 5 wherein said tube stop means comprises external key means.

7. Apparatus according to claim 6 wherein:

a. said tube support housing is mounted for limited movement in lateral directions;

b. said tube support housing includes a vertical slide having an aperture through which said keyed tube portion passes;

c. said slide includes keyway means allowing rotation of said keyed tube portion about its own axis through an angle of less than 180.

8. Apparatus for releasably coupling and latching together first and second units at least one of which is mobile, said coupling-and-latching apparatus compris mg:

A. a first powered mechanism mounted on a first mobile unit, said first mechanism including: a. an elongated member having a portion extendible in its axial direction, the extendible portion being also rotatable angularly about its own axis;

b. support means supporting the rearward end of said member on said first mobile unit for limited universal movement in the radial directions;

0. a reversible power drive to extend and retract said extendible portion;

(1. means for rotating said extendible portion angularly through an angle of less than 180;

e. a latch bar mounted at the forward end of said extendible portion and adapted to be moved angularly in either one direction through an angle of less than 180 and to be moved axially forwardly and rearwardly;

B. a second non-powered mechanism orysaid second unit, said second mechanism including:

a. a latch-bar keeper mechanism fixed mounted on said second unit and adapted to be engaged by said latch bar for latching said bar, and for unlatching said bar, according to the angular position of said bar and to subsequent axial movement of said extendible portion.

9. Apparatus according to claim 8 wherein:

a. said second mechanism includes at least one rotational stop for said latch bar preventing rotational movement of said latch bar in one direction beyond a selected angular latching position.

10. Apparatus according to claim 9 wherein:

a. said second mechanism includes an additional rotational stop for preventing rotational movement of said latch bar in either direction when said latch bar is in angular latching position and also in axial latching position.

11. Apparatus according to claim 10 wherein said latch-bar keeper mechanism includes a housing having an aperture therein of a shape and size to allow passage therethrough of said latch bar only when said latch bar is in angular unlatching position.

12. Apparatus according to claim 11 wherein said second mechanism includes guide means for guiding said latch bar into said housing aperture. 

1. Apparatus for releasably coupling and latching together first and second units at least one of which is mobile, said couplingand-latching apparatus comprising: A. A first powered mechanism mounted on a first mobile unit, said first mechanism including: a. a screw shaft; b. a reversible power drive for said screw shaft; c. a nut engaged with said screw shaft; d. means responsive to initial rotation of said screw shaft in either direction for allowing limited angular movement in said same direction of said nut and thereafter preventing rotational movement thereof in said same direction thereby to effect axial movement of said nut on said screw shaft in one direction or the other according to the direction of rotation of said screw shaft; e. a latch bar on said nut and adapted to be moved angularly in response to initial rotation of said screw shaft in either direction and thereafter to be moved axially forwardly or rearwardly on said screw shaft to effect self-latching and self-unlatching of said coupling-and- latching apparatus; B. a second non-powered mechanism on a second unit, said second mechanism including: a. a latch-bar keeper mechanism fixed mounted on said second unit and adapted to be engaged by said latch bar for latching said bar, and for unlatching said bar, according to the angular position of said bar and to subsequent axial movement of said nut on said screw shaft.
 2. Apparatus according to claim 1 wherein said second mechanism includes: a. at least one rotational stop for said latch bar preventing rotational movement of said latch bar in one direction beyond a selected angular latching position; b. additional rotational stop for preventing rotational movement of said latch bar in either direction when said latch bar is in angular latching position and also in axial latching position.
 3. Apparatus according to claim 2 wherein said latch-bar keeper mechanism includes a housing having an aperture therein of a shape and size to allow passage therethrough of said latch bar when said latch bar is in angular unlatching position.
 4. Apparatus according to claim 3 wherein said second mechanism includes guide means for guiding said latch bar into said housing aperture.
 5. Apparatus according to claim 4 wherein: a. said nut has an elongated tube portion; b. said tube is provided with rotational stop means; c. a support housing is provided on said first mobile unit through which said elongated tube portion of said nut passes; d. said tube support housing is constructed to allow limited movement of said tube within said support housing in all radial directions; e. said tube support housing is constructed to cooperate with said tube stop means to allow limited angular movement of said tube portion about its center axis.
 6. Apparatus according to claim 5 wherein said tube stop means comprises external key means.
 7. Apparatus according to claim 6 wherein: a. said tube support housinG is mounted for limited movement in lateral directions; b. said tube support housing includes a vertical slide having an aperture through which said keyed tube portion passes; c. said slide includes keyway means allowing rotation of said keyed tube portion about its own axis through an angle of less than 180*.
 8. Apparatus for releasably coupling and latching together first and second units at least one of which is mobile, said coupling-and-latching apparatus comprising: A. a first powered mechanism mounted on a first mobile unit, said first mechanism including: a. an elongated member having a portion extendible in its axial direction, the extendible portion being also rotatable angularly about its own axis; b. support means supporting the rearward end of said member on said first mobile unit for limited universal movement in the radial directions; c. a reversible power drive to extend and retract said extendible portion; d. means for rotating said extendible portion angularly through an angle of less than 180*; e. a latch bar mounted at the forward end of said extendible portion and adapted to be moved angularly in either one direction through an angle of less than 180* and to be moved axially forwardly and rearwardly; B. a second non-powered mechanism on said second unit, said second mechanism including: a. a latch-bar keeper mechanism fixed mounted on said second unit and adapted to be engaged by said latch bar for latching said bar, and for unlatching said bar, according to the angular position of said bar and to subsequent axial movement of said extendible portion.
 9. Apparatus according to claim 8 wherein: a. said second mechanism includes at least one rotational stop for said latch bar preventing rotational movement of said latch bar in one direction beyond a selected angular latching position.
 10. Apparatus according to claim 9 wherein: a. said second mechanism includes an additional rotational stop for preventing rotational movement of said latch bar in either direction when said latch bar is in angular latching position and also in axial latching position.
 11. Apparatus according to claim 10 wherein said latch-bar keeper mechanism includes a housing having an aperture therein of a shape and size to allow passage therethrough of said latch bar only when said latch bar is in angular unlatching position.
 12. Apparatus according to claim 11 wherein said second mechanism includes guide means for guiding said latch bar into said housing aperture. 